# [R-meta] converting p-values and t-statistics into correlation coefficients

Viechtbauer, Wolfgang (NP) wo||g@ng@v|echtb@uer @end|ng |rom m@@@tr|chtun|ver@|ty@n|
Thu Mar 16 18:23:00 CET 2023

```Hi Alan,

This is stuff I added recently, so it is in the 'devel' version, which you can install as described here:

https://wviechtb.github.io/metafor/#installation

I am quite close to releasing a new version of metafor via CRAN, but in the meantime, you can work with that.

Best,
Wolfgang

>-----Original Message-----
>From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On
>Behalf Of Alan Wilson via R-sig-meta-analysis
>Sent: Thursday, 16 March, 2023 16:04
>To: r-sig-meta-analysis using r-project.org
>Cc: Alan Wilson
>Subject: [R-meta] converting p-values and t-statistics into correlation
>coefficients
>
>Hey everyone - I have a student in my meta-analysis class who wanted convert p-
>values and t-statistics into correlation coefficients as part of their class
>project, but we are struggling to get correlation effect size calculations using
>metafor.  We have found an online resource through the Campbell Collaboration and
>could create an excel spreadsheet for the calculations, but we would prefer to
>use metafor for these conversions.
>
>Using this example, escalc(measure="COR", pi=-.07, ni=30), from
>https://wviechtb.github.io/metafor/reference/escalc.html, we get the following
>error.  It is not clear that pi is available in escalc.  Any advice how to
>overcome this hurdle is appreciated and will be shared with my class.  Thanks for
>any help.  alan
>
>Error in escalc(measure = "COR", pi = -0.07, ni = 30) :
>  Cannot compute outcomes. Check that all of the required
>  information is specified via the appropriate arguments.